Apparatus for semiwet development of photoprints



Au'g. 5, F. NAGELs ErAL 2,505,534

APPARATUS FOR SEMIWET DEVELOPMENT OF PHOTOPRlNTS md oct. 5. 1948SHEETS-Smm 1 MM Qgwil H TTRNEKF Allg- 5, 1952 F. NAGELS ET AL 2,605,684

APPARATUS FOR SEMIWET DEVELOPMENT OF PHOTOPRINTS Filed oct. 5. 1948 2Simms-SHEET 2 'I l l l l l l l l l O O` O o Q' o O O O O O O O O OJMPA/N55 Afl/afwas 5an/.vou5 55u-w l All/EN 71795 Patented Aug. 5, 1952UNITED STATES PATENT OFFICE APPARATUS FOBl SEMIWET DEVELOPMENT OFPHOTOPRINTSl Application October 5, 1948, Serial No. 52,924 In theNetherlands October 6, 1947 14 Claims.

The invention relates to apparatus for semi- Wet development ofphotoprints, adapted to apply a thin film of the developing liquid tothe material to be developed, said apparatus being provided with arotary liquid-applying-roller, having in its circumferential surface aplurality of channels or grooves extending transversely to the axis ofthe roller and further of the type in which a rotaryliquid-transmitting-roller is interposed in the path of the liquidsupply to the grooved applying roller.

Apparatus of the kind referred to is well known from U. S. Patent2,241,104 (to compare page 4, right column, lines 39-55) where thetransmitting-roller has been called an auxiliary roller. If certainrequirements described in this patent, are satised, apparatus of thekind referred to applies an even liquid layer of definite thickness (e.g. 8 cubic centimeters, viz. 8 grammes when the specic gravity of theliquid is l, per sq. metre) to the material to be developed. Thethickness oi the layer (expressed in the number of grammes per sq.metre) which the apparatus supplies to the photoprint material, however,is dependent on the speed with which it is operating (compare e. g. U.S. Patent 2,241,104, page 4, left column, lines 66-69). For a requiredthickness of the liquid layer, i. e. for a required application,determined by the requirements of the necessary development, theapparatus has to be operated at a fixed speed i. e. its speed has to becontrolled.

Consequently it is not possible to choose the speed arbitrarily, e. g.in adaptation to the speed with which the photoprinting paper is runningthrough a preceding exposure apparatus, or in adaption to other workingrequirements.

The object of the invention is to make the application of liquid lessdependent on the operating speed, meanwhile however maintaining anapplication roller having grooves or cross channels for the sake of itsinherent advantages. These advantages are that such channeled rollersonly cause a small stained edge at the end edge of the sheets to bedeveloped and only little starter (under development) at their startingedge. (For this starter compare U. S. Patent 2,241,104, page 2, leftcolumn, line 33).

For that purpose, according to the invention, in a developing machine ofthe kind referred to the capillary liquid applying roller is operated incontact with a liquid transmitting or auxiliary roller which replenishesthe channels of the applying roller, and the transmitting roller iscaused to cooperate with a raking or doctor- 2 device which limits thequantity of liquidtransmitted via its surface.

Normally a cross grooved applying roller has an excess of liquidavailable for application, sothat every demand for liquid that is madeby the material to be developed can be satisned (which demand increaseswith the speed)- In the apparatus according to the invention, theprovision with liquid of this grooved application roller itself islimited, with the result that the issue capacity of the roller can nolonger satisfy the demand unrestrictedly.

Even in case of largely varying speeds apparatus according to theinvention gives only a slight difference in application of thedeveloper. By designing the limiting raking or doctor-device adequatelyit is possible to fix rather exactly the number of grammes of developerper sq. metre applied by the cross grooved applying roller to thematerial to be copied. When the apparatus is thus set for theapplication of an average quantity of 8 grammes developer per sq. metrethe grooved roller will at a speed of eJg. 25-30 centimetres per minuteapply 7.5 grammes per sq. metre to material to be developed and passedover the roller, while this application is 8.5 grammes per sq. metre ata speed of e. g. 6 7 metres per minute.

Developments with '7.5 and 8.5 grammes per sq. metre do not differinconveniently from one another for the practice of the diazotypeprocess. By this invention good developments in practice are obtainedeven at speed variations of 1 to almost 30. This means an importantimprovement in the iield of diazotype-developrnent.

As has been stipulated in the U. S. Patent 2,241,104 the rotating crossgrooved applying roller which applies the developer to the material tobe developed must have a relatively large passage (compare U. S. Patent2,241,104, page 4, left column, line 12) e. g. 20-30 mm.2 (sq.millimetre) per decimeter length in order to meet with practicalrequirements.

Tests have been made with doctoring oi the cross grooves themselvesinstead of doctoring off the transmittingor auxiliary-roller, butwithout any favourable result.' v

It has appeared in the practice of the diazotype-development thatdifficulties may occur, when the developing machine according to theinvention is not in all its parts equipped for socalled "parallel run i.e. that the surface o1' the material under treatment and that of theroller cooperating with it are moving in the same direction. Preferablythe material to be developed Will be made to run with a speed equal oralmost equal to that of the grooved roller. Also stationary doctoringparts, which may cause troubles, preferably will be avoided. Diioultiese. g. may occur owing to the formation of crystal crusts from thedeveloper, to iilthiness of the developer and of the material to bedeveloped, to particles detached from the crusts etc. Consequently thedoctor-device is preferably of the kind comprising at least one rotatingroller.

In the drawings:

The Figures 1-5 are diagrammatic sectional elevations of variousembodiments of the liquidapplication-section of developing'apparatus.

Fig. 6 is a partial longitudinal section of a cross grooved roller.

Fig. '7 shows part of a doctor-blade or doctor'- knife.

Fig. 8 is a partial elevation of a roller adapted to be used as anauxiliaryor doctoring-roller.

v Fig. 9 represents part of the surface of another embodiment of such anauxiliaryor doctoring-roller.

In the Figures 1-5, I represents a roller of a diameter of millimetresconsisting of a metal core 2 coated with 21/2 mm. of a suitablesynthetic material 3, which contains helically wound cross grooves 6(see Fig. 6). The helix has a pitch of 0.5 mm., the grooves have a Widthof 0.15 mm. and a depth of 0.8 mm. So this cross grooved roller has apassage" of 2v00 0.8 0.15 :24 mm2 per decimeter of axial roller length.

In Fig. 5 there are two applying-rollers I and -I with cross grooves.This equipment is used for two-sided development. S represents in Figs.1-5 the material to be developed, which passes in the direction of thearrow over the grooved roller(s).

In Figs. 1-4 this material is kept in contact with the cross groovedroller by the guiding rollers 4 and 5.

They revolve in the direction of the arrows. In the developing apparatusaccording to Fig. 5 these guiding rollers are superfluous. It will beunderstood that all the developing apparatuses illustrated also haveother guiding and supporting devices as usually used in such machines.For the sake of simplicity they are not represented in the figures.

In Fig. 5, 'I and 'I' are auxiliary-transmission rollers cooperatingwith the cross grooved roller I and I' respectively. 'I'he guttershapedreservoirs 9 and 9 contain the developer liquid I0 and I0'. Theauxiliary "I in Figs. 1 to 4 function in essentially the same way,except that .in Fig. 3 roller 'I does not dip into the reservoir.

The various rollers rotate in the directions indicated by the arrows.

In Fig. 1 the transmission roller 'I by its rotation carries the liquidI0 upwards. The doctor blade I3, illustrated in Fig. 'I has recesses I4at distances of 4 mm. that are 0.1 mm. deep and 0.3 mm. wide. Roller 'Ihas a smooth surface. Thus in the cooperation of transmission roller 'Iwith doctor blade I3 there is a passage of 0.75 mm. 2 per decimetre ofaxial roller length. The quantity of liquid that passes through and islimited by this passage and which is carried to the cross grooved rollerI is such that roller I at speeds of cm. to 6 metres per min. appliesabout 8 grammes viz. 8 cubic centimetres per sq. metre to the material Sthat is to be developed.

In this arrangement the quantity of liquid taken by the material S fromroller I is also dependent on the surface structure of that material toa slight degree only. Instead of having a smooth surface, roller 'I canalso be provided with helically wound canals I5 on its surface, asrepresented by Fig. 8. When the helix of these canals has a pitch of 4.mm. and the canals I5 have a cross section of 0.1 x 0.3 nini. and whenthe doctor blade I3 is without recesses, consequently with a straightsliding edge, the result obtained will be quite analogous to that of asmooth roller 'I' combined with a doctor blade according to Fis. 7.

Fig. 2 illustrates an arrangement that is identical in principle to thatof Fig. 1.

The doctor blade I3 has been substituted by a doctoring-roller I6.chosen for this doctoring roller it will be possible to equip roller 'Iwith canals as described and as represented by Fig. 8. If on thecontrary roller 'i has a smooth surface, roller IS is to be equippedwith appropriate canals. t is also possible to equip the rollers 'I orIG with pits lI as represented in Fig. 9, which pits have been evenlydistributed over the surface of the roller, in such a manner that thecontents (the total volume) of the pits is approximately the same as thecontents (the total volume) of the canals described for roller I.

It is also possible to provide roller I and roller I5 both with canalsor pits; the limitation of the liquid then is determined by the sum ofboth the passages As a matter of fact this system of liquid limitationcan also be applied to the apparatus according to Fig. 1 and also tothose according to the Figures 3 to 5. As described before, the limitingpassages cause the cross grooved roller I to produce an application ofabout 8 grammes per sq. metre at various speeds. If desired this passageand consequently the liquid application can be decreased or (which,however, as a rule is undesirable) increased. In Fig. 3 the doctoringroller I 6 also acts as a supplying roller for the transmission orauxiliary roller 'I. It is mounted on the right-hand side of roller 'I,i. e. on the side on which the surface of roller I moves upwards anddrags liquid from the gutter 9. A stcwing meniscus is formed under theline of contact of the rollers 'I and IE. If roller I6 should be on theleft hand side of roller 1, the meniscus would be formed above thementioned line of contact. That embodiment is also possible. In Fig. 4the rollers I and I5 both act as supplying rollers. The upper part ofthe roller I, above the line of Contact with roller IG provides for thetransmission of liquid to the appli-- cation roller I.

As stated already the rollers l and I in r'g. 5 are the cross groovedrollers that apply liquid to both sides of the material S to bedeveloped. Cross grooved roller I cooperates with transmission roller`I; cross grooved roller I with transmission roller 'I'. In principle inthe manner of Fig. 2 the roller 22 doctors off roller 1 and roller 22doctors off roller 'I'. The applying rollers I and I can also besupplied with liquid via a series of rollers instead of one roller (aseries of rollers arranged one behind the other and contacting eachother in succession).

It is sufcient if one of them has a limited transmission, i. e. if it isdoctored to a certain extent as described above for the roller 'I and'I'.

As mentioned before developing apparatus according to the invention areparticularly adapted for use in combination with an exposure apparatusfor continuous exposure of photoprinting material e. g. diazotype paper.In practice printing is preferably done on a long uninterrupted If asmooth surface is' band of light-sensitive paper, which passes throughthe exposure apparatus e. g. over a glass cylinder surrounding a tubularlamp, the tracings to be copied being carried along between the glasscylinder and the band of light-sensitive paper. The transparency of thetracings varies in practice and in order to obtain the right exposuresthe exposing cylinder is made tok run quickly in case of a moretransparent tracing and slowly in case of a less transparent one. So theband cf material to be developed that leaves the exposure apparatus willhave a speed that is variable Within rather wide limits.

In combined exposureand developing machines this band will neverthelessbe required to pass as a Whole continuously through the developingmachine immediately after the tracings have been exposed and removed.

The developing machine according to the invention is extremely suitablefor that purpose, and its driving mechanism is advantageously adapted tomove with more than one speed, while in the combination with acontinuously operating exposure apparatus the driving devicesadvantageously can be chosen in such manner that the developingand theexposure-sections are operated at speeds adapted to one another, thespeed of the combination being variable. The speed variation can amountfrom a certain minimum speed to a fold speed.

In order to promote the straight running of the paper band all throughthe exposure and developing combination the developing section accordingto the invention is advantageously given a speed. of some per-centsgreater than that of the exposure section. Owing to this procedure someslip arises in the contact zone between the material S to be developedand the developing roller I and it is notoriously an advantage of thedeveloping machine according to the invention that no drawback isexperienced from such difference in speed.

The various rollers in the machine according to the invention can bemade of any suitable material.

They may be hard or weak. As to the doctoring zone care will have to betaken, however, that the passage keeps its required measurementsnotwithstanding the deformation taking place in weak material under theprevailing pressure.

The only general requirement for the material to be used is that it hasto be non corrosive. So preferably iron or brass is avoided but e. g.stainless steel, rubber, synthetic materials glass etc. are recommended.

What we claim is:

l. The method of reducing the speed-dependency of the rate ofapplication of a liquid photoprint developer to a moving photoprintmaterial from a roller surface formed with evenly distributedcapillary-active grooves extending transverse to its axis and holding anamount of such developer liquid per unit of surface area many timesexceeding that ever to be applied for developing a like unit of area ofthe material, which comprises, while rotating said surface in contactwith the moving material to apply the developer liquid thereto fromsaid'grooves, supplying developer for replenishing said grooves evenlyacross a part of said surface away from the material in a volume perunit of roller surface area not exceeding the volume required fordeveloping a like unit of area of the material.

2. The method of reducing the speed-dependency of the rate ofapplication of a liquid photoprint developer to a moving photoprintmaterial from a capillary roller surface formed with evenly distributedcapillary-active grooves extending transverse to its axis and holding anamount of such developer liquid per unit of surface area many timesexceeding that ever to be applied for developing a like unit of area ofthe material, which comprises, while turning said capillary surface incontact with the moving material, supplying developer liquid forreplenishing said grooves to a transfer roller surface turning incontact with said capillary surface, and doctoring the developer on thetransfer surface ahead of the capillary surface to a predeterminedvolume per unit of transfer surface area not exceeding the volumerequired for developing a like unit of area of said material.

3. The method of reducing the speed-dependency of the rate ofapplication of a liquid photoprint developer to a moving photoprintmaterial from a capillary roller surface formed with evenly distributedcapillary-active grooves extending transverse to its axis and holding anamount of such developer liquid per unit of surface area many timesexceeding that ever to be applied for developing a like unit of area ofthe material, which comprises, while turning said capillary surface incontact with the moving material, supplying developer liquid forreplenishing said grooves to a transfer roller surface turning incontact with said capillary surface, and limiting the supply on thetransfer surface ahead of the capillary surface to an amount per unit ofsurface area approximating that which the capillary surface applies to alike unit of area of the moving material at its minimum working speed.

4. The method of reducing the speed-dependency of the rate ofapplication of a liquid photoprint developer to a moving photoprintmaterial from a capillary roller surface formed With evenly distributedcapillary-active grooves extending transverse to its axis and holding anamount of such developer liquid per unit of surface area many times.vexceeding that ever to be applied for developing a like unit of area ofthe material, which comprises, while turning part of said capillarysurface in contact with and in the direction of the moving material,supplying developer liquid for replenishingsaid grooves to a transferroller surface turning in contact with and in the direction of anopposite part of said capillary surface, and doctoring the developer onthe transfer surface ahead of the capillary surface to a predeterminedvolume per unit of transfer surface area not exceeding the volumerequired for developing a like unit of area of said material.

5. In an apparatus for the semi-wet development of moving photoprintmaterial, a rotatable liquid applying roller having a circumferentialsurface to contact said material formed with evenly distributedcapillary-active grooves that extend transverse to its axis and hold anamount of developer liquid per unit of roller surface area many timesexceeding the amount ever required for developing a like unit of area ofthe material, a liquid transfer roller having its surface rotated incontact with said capillary surface, means for supplying developerliquid to said transfer surface, and a doctoring device contacting saidtransfer surface and forming with it ahead of said capillary surface alimited liquid supply passage of predetermined cross sectional areadistributed evenly over its axial dimension.

6..Invan apparatus for the semi-wet development of moving photoprintmaterial, a liquid applying roller having a circumferential surface tocontact said material formed with evenly distributed capillary-activegrooves that extend transverse to its axis and holdan amount ofdeveloper liquid per unit of roller surface area many times exceedingthe amount ever required for developing alike unit of area of thematerial,

vmeans for rotating said roller, aliquid transfer Vroller having itssurface rotated in contact with said capillary surface, meansforsupplying .dev eloper to said transfer surface, and a doctoring device`contacting said transfersurface and forming with it Aahead of saidcapillary surface a .limited liquid supply passage of `predeterminedcross sectional area distributed evenly .over its axial dimension, saidcross sectional areaper unit of .axial dimension being approximately thesame as the effective cross sectional area of the amount of saiddeveloper which `the capillary surface applies to a like unit dimensionof the moving material at its minimum working speed.

7. An apparatus asdescribed .in claim 5, said doctoring devicecomprising a-roller krotating in Contact with and in the direction ofmovement of the transfer roller surface.

A8. An apparatus as described in claim 7, said transfer roller surfacebeing formed uniformly with a multiplicity of evenly spaced recesses toprovide the limited supply passage.

9. An apparatus as described in claim '7, the contacting surface of saiddoctoring roller being formed uniformly with a multiplicity of evenlyspaced recesses to provide the limited supplyr passage.

10. An apparatus as described in claim 5, said doctoring devicecomprising a substantially sta-- tionary blade contacting said transfersurface at a multiplicity of points spaced evenly along its axis andhaving evenly spaced recesses `between said points forming said limitedsupply passage.

1l. An apparatus as described .in claim r5 comprising variable speedmeans for rotating saidV rollers to accommodate their surface speed tovarying speeds of movement of said material.

12. An apparatus as described in claim 5, said doctoring devicecomprising a roller rotating in contact with and in the direction of thetransfer roller surface, said liquid supplying means including acontainer for a body of said liquid into which the lowermost part ofsaid doctoring roller extends below the normal level of the liquid bodyv8 so that the doctoring roller bath carries liquid to and limits thesupply transferred on the transfer roller surface.

13. An apparatus as described in claim 12, the lowermost part of saidtransfer roller surface being disposed below said normal level.

14. Apparatus for the consecutive exposure and semi-Wet development ofmoving photoprint material, comprising an exposure cylinder rotatable atvariable speeds to expose a band of such material passing about thecylinder, a developer liquid applying roller arranged to engage saidband beyond the cylinder, said roller having its circumferential surfaceformed with evenly distributed ,capillary-active grooves that extendtransverse to its axisand hold an amount of developer liquid per unityof roller surface area many times exceeding the amount ever requiredfor developing a like unit of area of Asaid material, means for drawingsaid band about said cylinder and over said roller at variable speed,Variable speed means for rotating said roller surface in the directionof movement of said band, a, liquid transfer roller having its surfacerotated in contact with said capillary surface, means for supplyingdeveloper liquid to said .transfer surface, and a doctoring devicecontacting said transfer surface and forming with it ahead of saidcapillary surface a limited liquid supply passage of predetermined crosssectional area distributed evenly over its axial dimension. FREDERIKNAGELS.

JOHANNES HUBERTUS GERARDUS SELEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 687,481 Kammerer et al. Nov. 26,1901 801,552 Sherwood Oct. 10, 1905 911,241 Inman Feb. 2, 1909 2,241,104Grinten May 6, 1941 2,249,089 Murray et al. July 15,1941

2,265,856 Reed et al. Dec. 9, 1941 '2,524,818 McHugh Oct. 10, 1951FOREIGN PATENTS Number Country Date 298,965 Great Britain Oct. 18, v1928519,243 Germany Feb. 25, 1931 591,075 Germany Jan. 15,1934

